1. Field of the Invention
This invention relates to a low Btu gas burner suitable for burning low Btu gases in stable combustion.
2. Description of the Prior Art
Generally, gaseous fuels each have a lean limit of flammability. More specifically, when the ratio of a gaseous fuel to air or oxygen drops below a naturally determined value (lean limit of flammability), it becomes impossible to obtain combustion of the gaseous fuel or to cause the combustion thereof to be sustained in a stable state. A premixture below the lean limit of flammability (a mixture of the gaseous fuel with air or oxygen formed beforehand prior to combustion) is referred to as a low Btu gas. Difficulties as described hereinabove have been experienced in burning low Btu gases. It has recently been found that no lean limit of flammability practically exists for any low Btu gas when it is preheated to a temperature above a certain level. For example, in the case of a methane-air combustible mixture, it is possible to obtain complete combustion by preheating same to a temperature near 1400.degree. K.
If it is possible to obtain burners for practical use for burning low Btu gases based on the above finding, energy that has hitherto been wasted in the atmosphere could be recovered from thin fuel gases below their lean limits of flammability, thereby greatly contributing to conservation of energy. Additionally it would be possible to avoid air pollution by the low Btu gases released to the atmosphere in large amounts.
Development of the art for obtaining stable combustion of low Btu gases is earnestly desired not only from the standpoint of achieving technical innovation but also from the standpoint of conserving energy and avoiding environmental disruption. Various proposals have been made to provide an apparatus for burning low Btu gases. Some disadvantages are associated with apparatus of the prior art for burning low Btu gases and none of previous apparatus have ever succeeded in their production on a commercial basis. Some of the proposed apparatus are complex in construction and high in cost and some need a different form of energy to be supplied from outside for preheating the low Btu gases to an elevated temperature and, consequently, are uneconomical.